1. Field of the Invention
The present invention is directed to a guidance system for a fastener driving tool for guiding fasteners to a drive bore and thenceforward to a work surface.
2. Description of the Related Art
Many fastener driving tools are adapted with a magazine for feeding fasteners held in collations into a drive bore. Prior collations hold fasteners proximate their heads regardless of overall fastener length, so that long fasteners typically have a long shank portion below the collation and short fasteners typically have a short shank portion below the collation. Tools for driving fasteners typically have an opening into the drive bore long enough for the long shank portions so that a user may use the same tool for both short fasteners and long fasteners. However, a long drive bore opening provides an exit that may allow the short shank portions of short fasteners to tip or angle into the opening as short fasteners are driven, also known as“diving back” or “tumbling” into the magazine. Diving back may cause inaccurate driving of the fastener, jamming of the tool, or damage to the tool due to large forces needed to drive the fasteners into the substrate. These problems are exacerbated when combustion-powered tools are used to drive fasteners into concrete or steel.
One method that has been used to reduce diving back is to provide a plurality of nail head guide tracks in the magazine, one for each length of fastener, see U.S. Pat. No. 6,173,877. However, the magazine is only used to feed fasteners, not fasteners in collations. Also, a user must take great care to ensure that the head is placed in the appropriate channel for a fastener having a given length.
Another problem with prior fastener driving tools has been recoil of the tool due to firing. Many fastener driving tools have a fastener guide that recoils along with the tool body as the tool is fired so that the fastener guide lifts off of the substrate, which can cause the fastener to be in free flight between the fastener guide and the substrate, which may cause improper fastener placement or alignment. The fastener driving tool disclosed in the commonly assigned U.S. Pat. No. 6,138,887 teaches a fastener guide movable with respect to a tool body so that the fastener guide remains in abutment with the work surface as the tool recoils due to its firing. However, the fastener loading position of the tool moves with respect to the magazine so that the fastener in the drive bore may move up or down with respect to subsequent fasteners, which can allow more than one fastener to be loaded into the drive bore prior to firing or which can cause the fastener guide to impinge on the collation as it enters the drive bore. Firing a tool with multiple fasteners loaded in the drive bore or with a collation that is impinged by the fastener guide may cause jamming or damage to the tool.
What is needed is a fastener driving tool that overcomes the problems of the prior art.